A snow melting device is known in the art which is designed to melt snow and prevent freezing. The known device uses resisting linear elements such as nichrome wires sandwiched between coverings such as asphalt mortar layers in which the wires are arranged in a zigzag form. The manufacturing process requires at least three steps:
(1) to arrange the resisting elements on a first asphalt mortar layer; PA1 (2) to pour another dose of asphalt mortar onto the resisting elements laid on the first layer so as to form a heating body; and PA1 (3) to place a slab on the heating body wrapped in the asphalt mortar layers. Then the wrapped heating body is laid under the ground.
The following disadvantages have resulted:
Since the manual assembling work takes a long time, the asphalt mixture cools down before it is hardened enough. This results in the fragility of the roads. A fragile road causes the frequent breakage of the resisting elements.
In general, a protective layer such as of asphalt mixture requires a thickness of at least 25 mm sufficient to withstand traffic load, thereby increasing the weight of the road itself. In addition, the linear resisting elements have a relatively large thickness which result in rugged outward surfaces when they are wrapped in covering. When the protective layer is made of synthetic rubber, it is liable to deformation and breakage under traffic load. The fragile road surfaces cannot withstand traffic load, thereby causing the breakage of the inside resisting elements. It is difficult to find a broken spot of the resisting element in the coverage of the protective layers. It is particularly disadvantageous that a mechanical tool such as a finisher and a dumper cannot be used in assembling and installing the snow melting device under the ground.